#!/usr/bin/env python3
"""
audit_compact.py — Audit JSONL Compaction

Merges individual daily JSONL files from the last `window_days` into a single
compressed artifact: ops/audit/compact/tool_audit_last_{window_days}d.jsonl.gz

Useful for:
  - Faster forensic analysis (single file to read)
  - Archival before cleanup
  - Offline cost_analyzer runs

Usage:
  python3 ops/scripts/audit_compact.py \
    --window-days 7 \
    [--output-path ops/audit/compact] \
    [--dry-run] [--verbose]

Callable programmatically via run_compact().
"""

from __future__ import annotations

import argparse
import datetime
import gzip
import json
import logging
import os
import re
import sys
from pathlib import Path
from typing import Dict, List, Optional

logger = logging.getLogger(__name__)

_DATE_PAT = re.compile(r"tool_audit_(\d{4}-\d{2}-\d{2})\.jsonl$")


def run_compact(
    window_days: int = 7,
    audit_dir: str = "ops/audit",
    output_path: Optional[str] = None,
    dry_run: bool = True,
    repo_root: Optional[str] = None,
    verbose: bool = False,
) -> Dict:
    """
    Compact last `window_days` JSONL audit files into one .jsonl.gz.

    Returns:
      {source_files, lines_written, output_file, bytes_written, dry_run, errors}
    """
    if window_days < 1 or window_days > 30:
        raise ValueError(f"window_days must be 1–30, got {window_days}")

    root = Path(repo_root or os.getenv("REPO_ROOT", ".")).resolve()
    dir_path = (root / audit_dir).resolve()
    if not str(dir_path).startswith(str(root)):
        raise ValueError("audit_dir resolves outside repo root")

    today = datetime.date.today()
    cutoff = today - datetime.timedelta(days=window_days)

    # Find files within window
    source_files: List[Path] = []
    for fpath in sorted(dir_path.glob("tool_audit_*.jsonl")):
        m = _DATE_PAT.search(fpath.name)
        if not m:
            continue
        try:
            file_date = datetime.date.fromisoformat(m.group(1))
        except ValueError:
            continue
        if file_date >= cutoff:
            source_files.append(fpath)

    out_dir = (root / (output_path or f"{audit_dir}/compact")).resolve()
    if not str(out_dir).startswith(str(root)):
        raise ValueError("output_path resolves outside repo root")

    out_name = f"tool_audit_last_{window_days}d.jsonl.gz"
    out_file = out_dir / out_name

    lines_written = 0
    bytes_written = 0
    errors: List[str] = []

    if dry_run:
        # Count lines without writing
        for fpath in source_files:
            try:
                with open(fpath, "r", encoding="utf-8", errors="replace") as f:
                    lines_written += sum(1 for line in f if line.strip())
            except Exception as e:
                errors.append(f"{fpath.name}: {e}")
        if verbose:
            logger.info(
                "[dry_run] Would compact %d files → %s (%d lines)",
                len(source_files), out_file, lines_written,
            )
    else:
        out_dir.mkdir(parents=True, exist_ok=True)
        try:
            with gzip.open(out_file, "wt", encoding="utf-8") as gz:
                for fpath in source_files:
                    try:
                        with open(fpath, "r", encoding="utf-8", errors="replace") as f:
                            for line in f:
                                line = line.strip()
                                if line:
                                    gz.write(line + "\n")
                                    lines_written += 1
                    except Exception as e:
                        msg = f"Error reading {fpath.name}: {e}"
                        logger.warning(msg)
                        errors.append(msg)
            bytes_written = out_file.stat().st_size
            if verbose:
                logger.info(
                    "Compacted %d files → %s (%d lines, %d bytes compressed)",
                    len(source_files), out_file.name, lines_written, bytes_written,
                )
        except Exception as e:
            errors.append(f"Write error: {e}")
            logger.error("audit_compact failed: %s", e)

    return {
        "source_files": len(source_files),
        "window_days": window_days,
        "lines_written": lines_written,
        "output_file": str(out_file) if not dry_run else str(out_file) + " [not created]",
        "bytes_written": bytes_written,
        "dry_run": dry_run,
        "errors": errors,
    }


def _parse_args(argv=None) -> argparse.Namespace:
    p = argparse.ArgumentParser(
        description="Compact audit JSONL files into a single .gz archive",
        formatter_class=argparse.ArgumentDefaultsHelpFormatter,
    )
    p.add_argument("--window-days", type=int, default=7,
                   help="Compact files from last N days")
    p.add_argument("--audit-dir", default="ops/audit",
                   help="Relative path to audit directory")
    p.add_argument("--output-path", default=None,
                   help="Output directory (default: ops/audit/compact)")
    p.add_argument("--repo-root", default=None)
    p.add_argument("--dry-run", action="store_true")
    p.add_argument("--verbose", action="store_true")
    p.add_argument("--output-json", action="store_true")
    return p.parse_args(argv)


def main(argv=None):
    logging.basicConfig(
        level=logging.INFO,
        format="%(asctime)s %(levelname)s audit_compact %(message)s",
        stream=sys.stderr,
    )
    args = _parse_args(argv)
    result = run_compact(
        window_days=args.window_days,
        audit_dir=args.audit_dir,
        output_path=args.output_path,
        dry_run=args.dry_run,
        repo_root=args.repo_root,
        verbose=args.verbose,
    )
    if args.output_json:
        print(json.dumps(result, indent=2))
    else:
        status = "DRY RUN" if result["dry_run"] else "DONE"
        print(
            f"[{status}] sources={result['source_files']} "
            f"lines={result['lines_written']} bytes={result['bytes_written']} "
            f"→ {result['output_file']}"
        )
    if result["errors"]:
        sys.exit(1)


if __name__ == "__main__":
    main()